In the field of magnetic disk drives such as hard disk drives, there is proposed a magnetic disk drive including a magnetic head, a magnetic disk, and a housing containing the magnetic head and the magnetic disk, wherein the housing is filled with a low density gas such as He (helium) having a lower density than air. When the housing is filled with the low density gas, vibrations of the magnetic head and the magnetic disk can be reduced and, thereby, the performance of writing and reading data can be improved.
However, such a magnetic disk drive has a problem in which the low density gas begins to leak from the housing with time, and cannot be utilized. Accordingly, Japanese Patent Publication No. 2004-535647 (“Patent Document 1”) discloses a technology with which a warning is given when the density of helium in the housing reaches an unacceptable level.
The aforementioned Patent Document 1 only refers to the increase of the flying height of the magnetic head when the amount of the low density gas in the housing decreases, and it has not mentioned the possibility of decrease in the flying height of the magnetic head at all.